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Can I Use Pex Fittings on Polybutylene Pipe? (Answered)

We have heard people use the terms PEX fittings and Polybutylene pipe almost in an interchangeable way as if they were the same.

The very first fact that you need to be aware of is how these two fittings are completely different. The major query remains whether PEX fitting can be used on PB pipes after all.

Can I use PEX fittings on polybutylene pipe?

In order to use PEX fitting on polybutylene pipe or vice versa, transition couplings need to be used. Without the brass or copper crimp rings with transition couplings, the polybutene pipe is always bigger in diameter. The only similarity between the two pipes is that they are both made of plastic.

However, you would need to know that apart from being welded from the same material, PEX and polybutylene fittings are quite different. Although both are plastic, they are not made the same way.

Moreover, PEX fitting can only work on polybutylene with the help of a converter. The converter works as a ring that helps with the transition. Without it, one fitting cannot sit right into the other fitting.

Not only that, but you would also need crimp fitting along with special crimping tools to make the connection. Measuring and marking the insertion depth is vital in this process.

Will PEX fittings work on polybutylene?

If you attempt to use PEX fitting on polybutylene all by itself, it is unlikely that it might work. This is because Polybutylene is thinner compared to PEX fittings.

This means even if you fit a PEX fitting into a polybutylene, it would not be appropriate in measurements. You can expect the two fittings to be disproportionate and one to be looser than the other.

For that reason, the two fittings need to be connected using a transition ring or coupling.

3 reasons why you can use PEX fittings on polybutylene pipe:

You can use PEX fitting on polybutylene pipe by making certain alterations and adding extra connectors. Here are a few other reasons why you can use PEX fittings on polybutylene pipe:

Both are plastic fitting:

One of the biggest reasons why people think that PEX and PB fittings are interchangeable is because of the basic plastic material they are made of.

This is what distinguishes them from copper pipes and is another reason why they can be used on each other.

Use of connector:

Although the fittings are not quite of the same size, and become loose if one attempts to fit one PEX fitting into a polybutylene pipe, connectors are what makes it possible for the fittings to merge.

Best of both:

Since PEX fittings have a few benefits over PB and PB pipe fittings have some advantages over PEX fittings when you connect both fittings, one may enjoy the best of both plumbing systems.

Are PEX and polybutylene fittings the same?

When it comes to using transitions or connectors, one of the most common questions that are asked by many is whether PEX and polybutylene fittings are the same.

The confusion may arise for the reason that both PEX, as well as polybutylene, are plastic piping. These two piping are responsible for substituting all the pipe fitting in most homes that used to have copper in pipes.

The first of many differences between the two fittings is how PEX pipes have cross-linking polymer chain which is not the case in Polybutylene or PB pipes.

PEX piping for instance can take a lot more pressure than polybutylene pipes because of how the polymer is cross-linked. That’s why in many homes PEX fittings are used in areas that require facing high-pressure water flows.

PEX fittings are also better if you are willing to pump up very hot water. Since PEX is much more tolerant to heat, the plastic would not melt in any way. PB or polybutylene on the other hand may have more corrosion resistance, again due to its structural bonding in the material.

Due to similar issues with chlorine, PEX plumbing fittings may become weak over a long period of time. You may want to remember that in the United States, PEX fittings have been chosen over PB and the latter has been banned in the USA.

PB also has a better oxygen barrier, while PEX fitting will be more permeable as well. As PEX is too permeable, this can create several problems when used as fittings. Overall, PEX fittings are not the same as polybutylene pipe fittings due to technical differences.

How do you connect polybutylene to PEX?

Many people do not want to add the extra plumbing costs, which can be quite high based on the area you live in.

Although these plumbing works are best left to the experts, If you are still one of those who wish to utilize both the fittings, here are a few easy steps to help you with it:

Choose the right connector:

The very first step to connecting polybutylene to PEX through transition is to choose the right connector.

You would have to decide that on basis of what pipe will be used. For polybutylene or PEX, the only transition collars that are suitable have collar colors gray and tan respectively.

You may want to remember that white-collar fittings do not go with either but are only compatible with PVC.

Give a clean cut to the pipe:

Next is a crucial step where you would need to give a clean cut to the pipe. In this step, you may want to be precise and take necessary measurements if you wish.

You should be careful enough not to put scratches on the pipe with the scale, or other cutting tools you may be using. You may either use automatic or semiautomatic cutting machines to cut the pipe in the neatest possible way.

Measuring the insertion depth:

Subsequent to that, the tricky part involves you measuring the insertion depth.

These push-to-connect transition fittings come with varied insertion depth, based on which the size of fittings also varies. For instance, for a fitting size of 1 inch, you can expect an insertion depth in the pipe of about 1.31 inches.

Once measured, you can mark the position in the pipe. It is best to use a gauge for this step or marking and measuring the depth could become challenging.

Insert the connector and adjust accordingly:

The following steps are a breeze. Now the fitting you have chosen will go into both the pipes based on that insertion size. Insert the connector and adjust accordingly.

The biggest advantage to using these fittings is that you would not have to lose any time over the size, only if you have measured the insertion properly.

Run the water:

At last, run the water a few times to check if there are any loose connections.

Can I use PEX crimp fittings on a polybutylene pipe?

If you wish to use PEX crimp fitting on polybutylene pipe, it can only work if you use a specific type of coupling. In this case, you may use a brass barbed one that would fit either of the pipes.

The PB end will be blue so that one can mark it more conveniently. It is worth noting that PB is usually bigger than the PEX pipe without the crimp fitting. For the inside, you may have to use particular crimping tools as well.

It would also be beneficial for you to know that these PEX to PB transition fittings are available in one kit where you would also find the rings that are needed to be fit inside.

Is all GREY pipe polybutylene?

Indeed, polybutylene pipes are mostly indicated with the color grey. However, you may also find variations in colors like white or silver to indicate PB pipe as well.

More commonly, the seal may say with that stamp of PB2110 to indicate that the material of the pipe is polybutylene.

How to cut polybutylene pipe?

To cut a polybutylene pipe, you can use a variety of tools. Plumbers or professionals with access to kits use semi-automated cutting machines.

However, since these tools are less available to everyone, you can also use a knife, sharp hacksaw, or plastic pipe cutter to cut polybutylene pipe.

Can you glue polybutylene pipe?

Unfortunately, it is not possible to glue PB pipe with any kind of adhesive. Although many people think that glued poly pipes are used in the plumbing system, there is no such adhesive that could be used on PB fittings.

Final Thoughts

You can use PEX fittings on polybutylene pipe but you would need to connect it with the help of a ring. Transition coupling is the only way to connect the fittings as they are not the same in size. The two plastic fittings can also be used as a substitute for one another.